Found in the “Workshop Information System” (aka “WIS”) while reading up on the MY2011 9-5:
Rear Vision Camera System Operation
The components used in the rear vision camera system are the camera, located at the rear of the vehicle, and the navigation radio.
When the vehicle is placed in REVERSE, the body control module sends a 12 V signal to the rearview camera. This signal indicates that rear vision camera operation is required. Upon receipt of this signal, the camera will begin the power up cycle. The navigation radio also receives a serial message that indicates that reverse gear is engaged. When the radio receives the message it initiates the display start cycle. The rear vision camera transmits the video signal to the navigation radio through discrete + and – signal circuits. A metallic foil encases the video signal circuits and is tied to a shield ground circuit. This shield is designed to reduce electronic interference which may degrade the video signal and cause a distorted or otherwise degraded image.